1. Technical Field
The present invention relates generally to the field of tool joints and casing and, more specifically, to systems and methods for testing and/or calculating and/or projecting wear related to hardbands.
2. Description of Related Art
Drilling strings and casing strings are a large expense of subsurface drilling operations. Hardbands, also known as tool joint hardfacing, have been utilized for decades to prolong tool joint life of drill pipe by reducing outside diameter wear while simultaneously attempting to minimize wear to the inside diameter of the casing. Hardbands typically do not cover the entire length of the tool joint and may often be only about three inches or so in length.
In order to evaluate different types of hardbands and/or casing, wear producing machines are utilized to simulate downhole wear. For example, downhole wear may occur due to contact between the hardband and the inside of casing.
Machines to test hardband wear, some of which are discussed below, provide means for rotating the tool joint against a casing sample. Such machines have been in use for several decades. A measured contact load is applied between the tool joint and the casing sample. The casing sample is typically axially reciprocated while the tool joint is rotated. A fluid, such as one of various types of drilling fluids, may be circulated over the contact region between the tool joint and the casing. Various means for determining the wear are utilized, and the results may be applied to a graph for comparison and evaluation.
The present inventors have found that prior art wear machines to test hardbands over the last several decades tend to produce results that are not sufficiently accurate with respect to repeatability. The inventors herein disclose solutions that have improved repeatability of hardband wear tests up to 300%.
The following references describe the above and other related material:
The article entitled “Optimum Means of Protecting Casing and Drillpipe Tool Joints Against Wear,” by M. E. True and P. D. Weiner, printed in February 1975 in the Journal of Petroleum Technology, describes the results of 267 tool-joint tests and other related tests made under various conditions such as tests carried out in water, in two weights of water muds, and in oil-based muds. A machine is disclosed for carrying out the tests.
The article entitled “Casing Wear: The Effect of Contact Pressure,” by J. Steve Williamson, printed in December 1981 in the Journal of Petroleum Technology, describes a new test machine and experimental procedure used to study the effect of contact loads on casing wear. A machine is disclosed for carrying out the tests.
The article entitled “Casing Wear During Drilling: Simulation, Prediction, and Control” by J. M. Schoenmakers, printed in December 1987 in the Journal of Petroleum Technology, describes four case studies that show laboratory simulations of casing wear caused by rotating tool joint hardfacings correspond very well to field-measured casing wear. A machine is disclosed for carrying out the tests.
The article entitled “Casing Wear: Laboratory Measurements and Field Predictions” by J. P. White and R. Dawson, printed in March 1987 in the Journal of Petroleum Technology, describes an experimental program devised to measure casing wear in a full-scale test machine. A machine is disclosed for carrying out the tests.
The article entitled “Evaluation of New Tool Joint Hardfacing Material for Extended Connection Life and Minimum Casing Wear” by C. Marx, H. J. Retelsdorf, and P. Knauf, printed in March 1991 for presentation at the 1991 SPE/IADC Drilling Conference held in Amsterdam, describes a new testing facility allowing a combination of axial movement and rotation.
The article entitled “Recent Advances in Casing Wear Technology” by R. W. Hall, Jr., A. Garkasi, G. Deskins, and J. Vozniak, printed in February 1994 for presentation at the 1994 SPE/IADC Drilling Conference held in Dallas, Tex., provides a mathematical description of the casing wear process and an experimental determination of the wear factors which are an integral part of the casing wear model. The figures show a cross-section of a crescent-shaped wear groove in casing due to tool joint contact.
The article entitled “What Really Wears Your Casing When New Hardmetals Are Used” by F. J. Carlin, printed in February 1994 for presentation at the 1994 SPE/IADC Drilling Conference held in Dallas, Tex., discusses test results that indicate when new hardfacing materials are used that casing wear is dramatically reduced. A test machine is discussed.
While the above publications address many factors regarding the wear of drill strings and casing, the problem of repeatability of hardband wear tests remains to be addressed. Consequently, there remains a long felt need for improved equipment and methods, which significant reduce repeatability errors. Those skilled in the art have long sought and will appreciate the present invention, which addresses these and other problems.